You shall trample the serpent.

"You will crawl on your belly and you will eat dust all the days of your life." Genesis 3:14 [NIV]

When God cursed the serpent that he will crawl on his belly and eat dust all the days of his life, were serpents before that not crawling? Did God make the serpents before that to hop around or fly in the air?

The serpents before that used to crawl and even now do the same. God cursed not serpents but a specific serpent named Satan. It is not that Satan is a serpent but his character or nature is that of a serpent, very deceiving. When a serpent travels from one place to another he does not travel straight but in a zigzag direction. He is full of venom and wants to discharge it into those he hates. Even today serpents live in dust but they do not eat dust.

This serpent is also referred to as the dragon.

Revelation 12 [KJV]
7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8 And prevailed not; neither was their place found any more in heaven.
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.

The curse that God put on him was that he (and his whole lot) will be bounded of their powers and will have to live on earth all their life.

Revelation 12 [KJV]
1 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand.
2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,

God has bounded Satan till the last days from using his powers. Today we who live in faith are given authority over him and his powers. We too can rebuke Satan and bind his powers like God did from working over us and our family members and all areas of our lives. For it is written, the one who seek the righteousness and truth of God will trample down the serpent.

Psalm 91 [KJV]
13 Thou shalt tread upon the lion and adder: the young lion and the dragon shalt thou trample under feet.

Those who live in Christ can rebuke him and cast his forces to hell (abyss) as Jesus did. Jesus has assured us of this power.

Mark 16 [NIV]
17 And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues;

My dear brothers and sisters in Christ, do not be afraid of Satan and his works for he has no powers over you. God has bound him from doing so only if you believe in God's Word and live by it.

Confession (say this and act on it, to clam it)
I am a child of God and I live by the Word of God and Satan has no powers over me. I rebuke Satan and his works and bind him from working in my life and all areas of my life. I clam the protection of God and His Angles, for I pursue the righteousness and the truth of God.

The Word of God was given free to us, therefore we should also share it freely with others.
(All rights are with God)